<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }

        ul {
            position: fixed;
            bottom: 0px;
            left: 0;
            width: 100%;
            background: pink;
            padding-bottom: 100px;
        }

        li {
            height: 100px;
            width: 100%;
            background: blue;
            list-style: none;
            border: 1px solid #000;
            box-sizing: border-box;
        }

        div {
            max-height: 400px;
            overflow-y: auto;
        }
    </style>
</head>

<body>
    <ul>
        <div>
            <li>1</li>
            <li>2</li>
            <li>3</li>
            <li>1</li>
            <li>2</li>
            <li>3</li>
            <!-- <li>4</li> -->
        </div>

    </ul>
</body>
<script>


</script>

</html>